Muffler with chambers formed by three concentric tubes



Feb. 28, 1967 E. e. STRAW MUFFLER WITH CHAMBERS FORMED BY THREE CONCENTRIC TUBES Filed Nov. 25, 1964 INVENTOR. & 572% firv awlvg/s.

United States Patent 3 306,393 MUFFLER WITH GHAMBERS FORMED BY THREE CONCENTRIC TUBES Eldred G. Straw, Grass Lake, Mich., assignor to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Nov. 25, 1964, Ser. No. 413,688 2 Claims. (Cl. 181-48) This invention relates generally to exhaust systems for automotive vehicles, and more particularly, to improvements in automotive mufflers.

It is a general object of the present invention to provide an improved muffler construction of an extremely simple design.

It is a more particular object of the present 1nvention to provide a mufiler construction having improved means for partitioning various gas flow passages and chambers defined between the muffler housing and the internal exhaust gas flow tubes or conduits arranged therewithin.

It is still a more particular object of the present invention to provide an improved muffler construction of the above character wherein the partition means is integrally formed on either or both the gas flow tubes and the muffler housing.

It is yet a more particular object of the present invention to provide an improved mufller construction of the above character wherein the aforesaid partition means are formed by necking down or expanding the gas flow tubes and/or muffler housing.

Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a longitudinal cross-sectional view, partially broken away, of a preferred form of a muffler construction of the present invention;

FIGURE 2 is a transverse cross-sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is a transverse cross-sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is a fragmentary cross-sectional View of a muffler construction embodying an alternate form of the present invention; and

FIGURE 5 is a fragmentary cross-sectional view of a muffler construction embodying still another form of the present invention.

Referring now to FIGURES 1 through 3 of the drawing, a muffier construction 10, in accordance with a preferred embodiment of the present invention, is shown as comprising a hollow cylindrical external shell or housing 12 which is necked down or swaged radially inwardly at its opposite ends to form reduced diameter inlet and outlet bushings 14 and 16. Extending coaxially within the housing 12 is a hollow cylindrical gas flow tube or conduit 18 whose outer diameter is approximately equal to the inner diameter of the bushings 14 and 16. The tube '18 is rigidly secured within the housing 12 by having its opposite ends spotweldcd or similarly secured within the inner ends of the bushings 14 and 16. as seen in FIGURE 1. A hollow cylindrical inner shell 20, which has a diameter equal to approximately one half the difference between the diameter of the housing 12 and the diameter of the gas flow tube 18, extends coaxially of the mufiler and is located approximately half way between the inner periphery of the housing 12 and the outer periphery of the tube 18. The inner shell 20 divides the annular space between the housing 12 and the tube 18 into two concentric annular chambers 22 and 24. A plurality or bank of fine flat louvers, generally designated 26, are formed around the tube 18 to provide a predetermined amount of communication between the interior of the tube 18 and the annular chamber 24.

In accordance with the principles of the present invention, a gas-tight partition is formed at each end of the annular chamber 22 through the provision of a pair of radially inwardly projecting and generally U-shaped folds or pinched down sections 28 and 30 which extend entirely around the housing 12 and engage the outer periphery of the inner shell 20 in gas-tight joints, as seen at 32 in FIGURE 1. The sections 28 and 30 may be formed in the housing 12 by employing conventional swaging or tube reducing techniques and swaging the ends of the housing 12 radially inwardly to the inner diameter of the sections 28 and 30. Thereafter, the ends of the housing 12 may be expanded by forcing the ends of the housing 12 into engagement with a suitable expanding mandrel or die, thereby forming the U-shaped sections 28 and 30 shown in FIGURES l and 3.

A gas-tight partition is provided at each end of the annular chamber 24 by means of a plurality (four) of pinched down areas, generally designated 34, that are formed at each end of the inner shell 20 and sealingly engage the outer periphery of the opposite ends of the tube 18. The pinched down areas 34 are preferably equally circumferentially spaced around the shell 20, the excess material adjacent each of the areas 34 being gathered into a plurality (four) of generally U-shaped outwardly projecting folds or pinches, herein designated by the numeral 36. It will be noted that the pinched down areas 34 are adapted to contiguously and tightly engage the outer periphery of the tube 18 and therefore serve to provide the aforementioned gas-tight partitions at the ends of the chamber 24 and also to rigidly support the inner shell 20 within the muffler construction 10.

Referring now to FIGURE 4, in a slightly modified form of the muffler construction 10 embodying the present invention, a gas-tight partition is formed at the end of the annular chamber 22 by means of a radially outwardly projecting end section, generally designated 38, that is formed on the end of the inner shell member 20. In particular, the end section 38 comprises a substantially flat radially outwardly extending portion 40 which terminates at its radially outer edge in an annular, longitudinally extending flange portion 42 that is contiguously engaged with the inner periphery of the muflier housing 12. As seen in FIGURE 4, the flange portion 42 is adapted to be spotweldcd or similarly secured to the inner periphery of the housing 12 such that the section 38 rigidly supports the one end of the inner shell 20 within the muflier construction 10.

Referring now to FIGURE 5, in still another slightly modified form of the muffler construction 10 embodying the present invention, the inner shell 20 is formed with the hereinbefore described pinched down areas 34 and -shaped folds 36 in an identical manner as was described in connection with FIGURES 1 through 3; however, the gas-tight partition formed at the end of the chamber 22 is provided in a slightly different manner than that which is illustrated in FIGURE 1. In particular, a partition is provided at the end of chamber 22 by having the end of the muffler housing 12 necked down or swaged radially inwardly into engagement with the outer periphery of the gas flow tube 18. This is accomplished in a manner such that the housing 12 has a substantially fiat end wall, as seen at 44, which terminates at its radially inner edge at the inner (right) end of the bushing 14. It will be seen that this modification of the muflier construction 10 of the present invention minimizes the material in the swaged portions of the housing 12 and also minimizes the outer diameter of the muffier construction 10 adjacent the opposite ends of the housing 12.

A primary feature of each of the hereinbefore described embodiments of the present invention resides in the fact that the various partition means are provided without the use of any separate or independent partitions r header members, these members being replaced by the various swaged and expanded sections of the muflier housing and gas flow tubes and shells contained therein. This feature is of importance in that the partitions are integrally formed on the existing muffler components, thus minimizing to the extreme, the cost of producing the muffler construction, together with substantially reducing the assembly time and expense involved in the mass production thereof. Furthermore, since the partition means constitutes an integral portion of the muffler components, the possibility of any relative movement or vibration between the partition means and the mufller components on which the partition means are formed, is virtually eliminated.

While it will be apparent that the embodiments of the present invention illustrated herein are well calculated to fulfill the objects above stated, it will be appreciated that the present invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A muffier for silencing sound in flowing gases comprising an elongated tubular housing having annular reduced diameter portions at opposite ends forming a gas inlet and a gas outlet, a perforate gas flow tube extending through said housing and having opposite ends supported in said reduced diameter portions, an intermediate tube in said housing around at least a portion of the length of the flow tube, said tubes and housing being substantially coaxial, said housing having a radially extending annular tube support and partition portion engaging the outside of said intermediate tube comprising an annular inwardly extending fold of a U-shaped cross section wherein the opposite legs of the U are substantially in contact with each other.

2. A mufller as set forth in claim 1 wherein said intermediate tube has a reduced diameter portion engaging the outside of the flow tube, said just mentioned reduced diameter portion comprising four substantially equally spaced arcuate segments embracing the flow tube and interconnected by four radially extending U-shaped folds formed in said intermediate tube.

References Cited by the Examiner UNITED STATES PATENTS 1,878,424 9/1932 Oldberg 181-48 2,035,500 3/1936 Nulty 181--48 2,188,202 1/1940 MacKenzie et a1 18148 2,194,457 3/1940 Cary. 2,233,341 2/1941 Cary 181-48 2,357,792 9/1944 Powers 18148 2,367,753 1/ 1945 Buck. 2,930,440 3/ 1960 Fetzer et a1. 3,104,735 9/1963 Ludlow et al. 3,219,142 11/1965 Deremer 18161 X 3,242,558 3/1966 Selig.

FOREIGN PATENTS 1,351,921 12/1963 France.

892,780 3/ 1962 Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

R. S. WARD, Assistant Examiner. 

1. A MUFFLER FOR SILENCING SOUND IN FLOWING GASES COMPRISING AN ELONGATED TUBULAR HOUSING HAVING ANNULAR REDUCED DIAMETER PORTIONS AT OPPOSITE ENDS FORMING A GAS INLET AND A GAS OUTLET, A PERFORATE GAS FLOW TUBE EXTENDING THROUGH SAID HOUSING AND HAVING OPPOSITE ENDS SUPPORTED IN SAID REDUCED DIAMETER PORTIONS, AN INTERMEDIATE TUBE IN SAID HOUSING AROUND AT LEAST A PORTION OF THE LENGHT OF THE FLOW TUBE, SAID TUBES AND HOUSING BEING SUBSTANTIALLY COAXIAL, SAID HOUSING HAVING A RADIALLY EXTENDING ANNULAR TUBE SUPPORT AND PARTITION PORTION ENGAGING THE OUTSIDE OF SAID INTERMEDIATE TUBE COMPRISING AN ANNULAR INWARDLY EXTENDING FOLD OF A U-SHAPED CROSS SECTION WHEREIN THE OPPOSITE LEGS OF THE U ARE SUBSTANTIALLY IN CONTACT WITH EACH OTHER. 